With plenty of expensive lever action suction cup camera mounts on the market, I decided to build my own, after seeing a similar one here on Instructables. Harbor Freight has plenty of vacuum "lifters" of different sizes and low prices. I picked the smallest they have on the shelf, the Mini Suction Cup, item 46900, two inches in diameter. It is described as being able to lift 15 pounds. I tested it with a digital scale and stopped pulling at 32 pounds, so as to not break the handle. It must be attached to hard, non-porous, flat surface, or it will not hold.
My camera to be mounted is a ContourHD and only weighs five ounces with the tripod mount, so I figure there won't be a problem with the weight. Not shown in any of the photos is a safety lanyard, to "rescue" the camera should the mount lose grip. I will most certainly be using one.
This instructable could be easily scaled up for larger suction cup sizes, although the material weight may get out of hand.
Step 1: Materials, Tools Used
Harbor Freight Mini Suction Cup 46900
1/8" thick by 2" wide aluminum flat, slightly less than six inches per unit, ordinary hardware store item
#8-32 bolts, #8 rivnuts (had them in my parts bin, could have used any bolts and nuts of similar size) approx 1/2" grip length
1/4x20 thumbscrews, about 1" long. Again, I had some 1 1/2" in the pile, so they got used.
threadlock adhesive, aka Locktite or Permatex (medium strength)
drill bits, 1/8", 3/16",1/4"
hacksaw, band saw, center punch, file, tabletop belt sander
scrap cardboard from a frozen dinner box, pencil
Step 2: Make a Pattern
The vacuum clamp, when closed and locked, has a small gap created by a pair of plastic pins protruding from the fixed handle. The aluminum flat stock has to fit around those pins. One could omit this step and carve away the pins, but I feel they add some slight structural stability to the aluminum.
Clamp the cardboard in the handle and trace around the curve and around the pins.
Step 3: Transfer to the Aluminum
I used a center punch to locate the pin holes and traced the pattern to the aluminum. Note that the cardboard is hanging off the edge of the aluminum stock slightly. This is due to the arc that the moving handle makes as it closes, requiring a bit of clearance. I realize now that I could have simply cut off an eighth of an inch or so and had more consistent results.
The inner outline of the handle was of no real value and I had started to cut out the cardboard before I realized that. The inner portion of the cardboard is useful to locate the screw holes used to secure the two pieces of aluminum together.
Cut out the aluminum at the outline, file and sand to remove burrs and improve the appearance.
Step 4: Drill for Pins, Bolts, Rivnuts
The pins on this clamp are sized so that a one-eighth drill bit works perfectly. I was lucky enough to get the alignment spot-on and the pins fit precisely into the holes.
After making a rough guess for the "clamping" screws, I drilled to 3/16" the holes show in the photo. The rivnuts are visible on photo three of this group and pressed into place in photo four.
I was doing half the work in the garage and half out on the trash receptacle, in the sun. The aluminum and the rivnuts heated up to the point where I was not able to push the rivnuts into the holes. After letting them cool in the shade, they slid right into place.
If you are using screws and nuts, you won't have this concern, obviously.
Step 5: Convenient Rivnuts
Rivnuts are a combination rivet and nut, obviously. They can be used as a blind nut, and also to join material together in the same manner as a pop-rivet, if the materials are thin enough. WIth this one-eighth inch thick aluminum, it's really too thick for "proper" use, but it has enough strength for this application.
The rivnut is threaded onto the tool, then pushed into the hole. The handles are squeezed, deforming and locking the rivnut into place. The tool is then removed. This particular tool has enough leverage to pull the threads right out of the rivnut. I've done this more than once, and simply drill out the damaged one and try again.
Step 6: Camera Mount Plate
Cut the remaining piece of aluminum to desired width. I used the same width as the clamp handle, but one could cut it longer if more flexibility in mounting the camera is desired. I may do just that to provide for a mount location closer to the surface on which the suction cup will be attached. I can also angle the flat stock to achieve the same or similar results.
Eyeball a hole for the screw, drill and attach with a screw.
On the flip side, I used a smaller diameter drill bit to clear the threads of the rivnut, to make a mark showing me where to drill the second hole. In the first clamp, seen in the background, the holes were perfectly positioned and the plates attached just fine. In my second attempt, the holes were about one one-sixteenth off, and I had to enlarge them to get the screws to engage.
Because the rivnuts were attached to a thick piece of material, the length of the rivnut prevented the opposite flat stock from sitting flush on the handle. After getting the holes drilled and confirming proper positioning, I then used a larger drill bit to "counter-sink" the back side of the main mounting plate, which allowed the rivnuts to recess into the plate and give me the clamping force I wanted.
Using bolts and nuts will allow for greater latitude for error in the drilling of the holes.
After final assembly, drill 1/4" holes for the thumbscrews and wing nut lock nuts.
I applied Permatex thread-lock adhesive, also known as Loctite to the threads. Nuts and bolts users could purchase nylon locking nuts as a suitable replacement.
Step 7: Locked and Loaded
Again, I don't have a lanyard attached, but there's no way I'm going to risk losing my camera and my five or ten dollar camera mount to a hard bump. I think the trickiest part will be determining the best place to attach the other end of the cord. Since my velomobile is composed of hard, flat, non-porous surfaces, I have great flexibility in mounting my cameras. I'll be shooting, literally, for those "Top Gear" angles of the wheels spinning, making turns, taking fast corners, perhaps a hard bump now and then, but not intentionally!
The other instructable, which I could not find, used larger suction cups and simply drilled and bolted through the handle. This little dinky suction cup would too easily fracture if I had drilled. I can also easily remove the mount and the suction cup is as-new. It means I can also buy a replacement and bolt it on should the rubber dry out on this one.